Filoviruses are CDC category A priority pathogens that can subvert host immune systems to facilitate viral replication, resulting in human case fatality rates as high as 90%. The Ebola virus (EBOV) RNA-dependent RNA polymerase (RDRP) complex is critical for replication. However, the mechanisms regulating viral RNA synthesis or the factors that modify viral replication are not understood. The Protein Production and Protein Interaction Core (Core B) will provide critical reagents and support for the overall scientific mission and facilitate the characterization of viral-viral and viral-host interactions. Specifically, Core B will provide a unique set of standardized reagents and validation data that will be disseminated amongst the Projects and Cores. Core B has prioritized experiments in order to ensure that reagents will be readily available for use by the Projects and Cores. Core B will generate milligram quantities of highly purified recombinant viral RDRP proteins that will be used for evaluation of strain similarities/differences and for both monoclonal antibody development and synthetic antibody generation. Core B will also produce recombinant novel host factors identified by Projects 1 and 3 that will be used to validate and characterize interfaces between the EBOV RDRP complex and novel host factors.